This project is concerned with the processing of complex sounds by the primate cerebral cortex and related brain structures. Special attention is being paid to sounds used by primates in intra-specific communication to determine which cues are used by the brain and the animal to distinguish between the various elements of the communication repertoire. The principal experimental methods involve recording single neuron discharges from auditory areas in awake sitting squirrel monkeys. Both naive and trained monkeys are employed, and the acoustic stimuli presented to the animals include both traditional laboratory generated signals and vocalizations previously recorded in various contexts.